It’s the book that launched a thousand teenage fantasies. Hugh Hefner’s “Little Black Book,” filled with names, phone numbers and observations on scores of women, goes on display today at the Chicago History Museum. The display is a part of the museum’s Unexpected Chicago exhibit, which showcases items from the institution’s collection of 22 million historic and occasionally eccentric artifacts.

The book was obtained from Christie’s in 2003 and has a “while you were away” note tucked inside.

The Chicago native launched Playboy in 1953, riding (and in many ways shaping) the postwar sexual revolution. It was during this time that the media mogul used his credit card-sized book to jot down his impressions of women, many of whom may have graced the pages of the popular magazine. Hef’s book is as much an address book as it is a diary, business log and artists’ sketchbook (if you can call what Hefner does art). “Everything from typical contact information to obscure observations to secret phone numbers and code words, for rendezvous, were recorded within its pages,” the museum says, according to an article on Crain’s Chicago Business website. It goes on display as the company Hefner founded closes its Chicago offices and consolidates its operations in Los Angeles.

These days, the idea of a little black book almost seems quaint. A plot staple in subpar romantic comedies and chick lit, they’re rapidly becoming phased out in favor of smartphone address books and online dating services. The next lothario’s diary to get immortalized in a museum display could well take the form of an eHarmony profile.